CRX: Re: Physics lesson, and a stop to all this bickering about tires andsizes and hydroplaning.

[Brian-SubCultureNM]

You've made some decent points, but haven't taken all the variables into consideration. Your formulas assume a perfectly flat tire, one with no tread pattern at all (tread pattern will, of course, take precious square-inches away from your total contact patch.) However, a well designed tread pattern will evacuate water from underneath its contact patch, thus nullifying a large portion of your assumptions.   Anyway, I'm not an advocate for driving as you would on dry pavement when it's wet. Of course, here in NM, rarely do we have to worry about anything more than a few rain drops on the pavement. Also, as far as the truck is concerned, 1) it has an air-bag suspension which allows for a lot of slop in its handling - in other words, it doesn not maintain constant down-force on any surface; 2) it's body-dropped and has had a large portion of its bed structure removed, so the weight over the drive wheels is probably no heavier than a CRX; 3) as mentioned, it is front-heavy RWD, which lends itself to more handling problems (and less predictable handling problems with the 'bags) than a FWD CRX. Therefore, when you take all this into consideration, it should handle even worse on wet pavement than the CRX. It didn't, and the tire tread and compound has a lot to do with that.   Finally, congratulations on your door handles (seriously.) I would be curious as to how long you've had them done and whether-or-not you've started to experience shrinking of the JB Weld. If you haven't, you will. Believe me, having a lot of experience with custom body mods, there's rarely a time that they are 100% trouble-free. THis isn't a critique of your work, it's just a fact. We've had to have one door and the tailgate handle on our truck re-done because of cracking. It happens to the best of them!   Brian ----- Original Message ----- From: Jeremy Bass To: [EMAIL PROTECTED] Sent: Friday, January 31, 2003 3:54 AM Subject: CRX: Physics lesson, and a stop to all this bickering about tires and sizes and hydroplaning. An end to all of this hydroplaning crapola...  Welcome to Jeremy's weird world of physics...   Exibit A: Frontal Resistance...  The more surface area you present in the direction of the movement, the more resistance you create and the more force you need to overcome that resistance.   The surface area is the contact patch of the tires.  The direction of the movement is the tires penetrating the water. The resistance is how hard it is for the contact patch of the tires to penetrate that water.  More force would mean more weight pushing down on the tire or traveling at a lower speed so that the tire has less water to penetrate.   In other words...  If you were in a 1990 Honda CRX si, and hit a puddle with a depth of .40 in. or greater of water at 50mph with stock 185/60/14 tires you would be less likely to hydroplane than if you were to hit water with 205/40/16s.  I use .40 inches of water because it rids me of variables such as tire tread pattern and road surface, because your tire is as good as slick in water that deep. If your tread is deeper than .40 inches on your crx you need to buy tires that are not for off-road use....    Now, a stock 1990 Honda CRX si with 185/60/14 tires at 28psi weighs 2174lbs, and has a weight distribution of 62% front and 38% rear. Therefore, the front tires are putting 1396.2 lbs to the pavement which is a scant 698.1 lbs each.  So, in exactly .40 in. of water and a contact patch of 32.8 sq. inches, it would take water pressurized to anything above 21.28 psi to lift the car from the surface of the road. ( I think that is around 51mph??, but that doesn't matter right now )   SO, if the tire variables increase the contact patch of the tire, it lowers the water psi needed to lift the vehicle, and increases the likelyhood of hydroplaning.    THEREFORE THESE STATEMENTS ARE FACTS:  Tire outside diameter DIRECTLY affects hydroplaning. (minimaly)  (18 inch rims must use larger than stock OD) The width of the tire DIRECTLY affects hydroplaning. Tire pressure DIRECTLY affects hydroplaning. The weight of the car DIRECTLY affects hydroplaning. Speed...  Duh.   Thank you ladies and gentlemen..    (I'm sure my english is not perfect, nor spelling. But the numbers can be checked with a fine tooth comb.)  oh, and your canyon carving truck with the big fat tires weighs way more than our lil rexes so your example is null because you have more "FORCE"...  nanny nanny boo boo....   So, may we please quit bickering??! : )